adding a Virtual Hard disk to Hype-V host

Posted on 2013-12-05
Medium Priority
Last Modified: 2014-11-12
I have Hyper-v setup on a Windows 2008R2 Enterprise server.

I have some virtual servers there too.

I have a couple of USB drives that I have plugged into the Parent machine. I want these 2 to be seen as external hard disks to all the Virtual machines.  I am planing to use these as backup drives.

I am trying to achieve this by adding the 2 USB disks as Virtual Hard Disks under the Hyper-V manager.

There are however 3 Disk type options.
1. "Fixed Size"
2. "Dynamically Expanding"
3.  "Differencing"
I was hoping the option 3  "Differencing" ( as in the screenshot ) would be the best ?
Is this a "safe" option ? I don't want my Host machine to have issues if I choose the wrong option.

and if anyone can explain what these optoins are - that would be great too.
Question by:indikad
  • 2
LVL 61

Accepted Solution

Cliff Galiher earned 1440 total points
ID: 39699869
You will not get these drives to appear as "external" drives to the VMs, no mater which option you choose. They will appear as drives, and even as hot swappable drives if you use he virtual SCSI interface, but as USB/removable drives.

as far as which option, fixed is almost certainly your best bet. The other two are for specific scenarios that, if you wanted or needed them, you'd know. And writing up a full description of each option would turn his answer into a small novella. And TechNet already has hat, so it'd be a redundant novella at that.

But suffice it to say, differencing is definitely NOT what you want here.

Author Comment

ID: 39699881
Hi cgaliher,

Thanks for the reply.

Ok I don't mind if the drives appear as external drives or not as long as ai can acess them as a disk for backup purposes.

guess then I will go with the optopn 1 - Fixed.

I will also bookmark TechNet.
LVL 40

Assisted Solution

Mahesh earned 160 total points
ID: 39700635
How many virtual servers and USB drives do you have ?
Because if you want to attach dedicated HDD to VM, then that HDD must be need to taken offline on parent machine and then can be used with one VM only at a time as SCSI drive.
Correct me if I am wrong


Author Closing Comment

ID: 39828573
Thanks all for help

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